During the period from 04/01/78 to 03/31/79 two types of experiments will be performed: 1) experiments that pertain to the neuroendocrine control of nutritional balance, and 2) experiments that deal with the neural mechanisms of pain. The first group of experiments will evaluate the effects of the growth hormone on the glucosensitive neurons of the brain stem nuclei in the generation of the thalamic pain code. All experiments will be performed on animals (rats, cats) under general anaesthesia. Electrophysiological methods (Brain Res. 49: 335, 1973 and 103: 425, 1976) will be used. In experiments pertaining to the action of the growth hormone, spontaneous firing of single hypothalamic neurons will be accumulated in a computer over a period of 1,000 seconds under control conditions. This value will be than compared to a similar value obtained after an intracarotid infusion of the growth hormone. In experiments pertaining to the neural mechanisms of pain, attempts will be made to modulate the thalamic code for pain (Brain Res. 103: 425, 1976) by electrical stimulation of numerous brain stem nuclei, e.g. the nuclues centrum medianum. It is expected that these studies will 1) contribute to the knowledge about the neuroendocrine influence on dietary preferences and body weight, and 2) provide the necessary information to increase the effectiveness of thalamotomies for the management of intractable pain.